XML (Extensible Markup Language) is a flexible way to
create common information formats and share both the format and the data
on the World Wide Web, intranets, and elsewhere. For example, computer makers
might agree on a standard or common way to describe the information about
a computer product (processor speed, memory size, and so forth) and then
describe the product information format with XML. Such a standard way of
describing data would enable a user to send an intelligent agent (a program)
to each computer maker's Web site, gather data, and then make a valid comparison.
XML can be used by any individual or group of individuals or companies that
wants to share information in a consistent way.
XML, a formal recommendation from the World Wide Web Consortium (W3C), is
similar to the language of today's Web pages, the Hypertext Markup Language
(HTML). Both XML and HTML contain markup symbols to describe the contents
of a page or file. HTML, however, describes the content of a Web page (mainly
text and graphic images) only in terms of how it is to be displayed and
interacted with. For example, the letter "p" placed within markup
tags starts a new paragraph. XML describes the content in terms of what
data is being described. For example, the word "phonenum" placed
within markup tags could indicate that the data that followed was a phone
number. This means that an XML file can be processed purely as data by a
program or it can be stored with similar data on another computer or, like
an HTML file, that it can be displayed. For example, depending on how the
application in the receiving computer wanted to handle the phone number,
it could be stored, displayed, or dialed.
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